Adjustable muzzle choke



July 14, 1959 Filed March 2, 1955 R. M. CUTTS ADJUSTABLE MUZZLE CHOKE 3Sheets-Sheet 1.

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INVENTOR Riol-cbrd M. Cubi's.

' Ga/nu/Law,

ATTORNEYS July 14, 1959 R. M. cuTTs 2,894,348

ADJUSTABLE MUZZLE CHOKE Filed March 2,1955 3 Sheets-Sheet 2 ATTORNEYSJuly 14, 1959 Filed March 2 1955 R. M. CUTTS ADJUSTABLE MUZZLE CHOKE 3Sheets-Sheet 3 II-JYENTOR Richard M. Cul'bS.

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' ATTORNEYS ADJUSTABLE MUZZLE CHOKE Richard M. Cntts, The Plains, Va.

Application March 2, 1955, Serial No. 491,625

Claims. (Cl. 42-79) This invention relates to adjustable muzzle chokesand more particularly to such chokes which are intended primarily foruse with shotguns to provide uniform and adjustable shot patterns.

Heretofore various adjustable choke devices have been suggested and usedwith shotguns and have enjoyed wide commercial acceptance. These priorart devices, however, include various undesirable features which areovercome in the novel adjustable choke device of the present invention.For example, in certain prior art adjustable choke devices inadequatesupport is provided along the length of the yielding segments which whenbent from the cylindrical to the conical provide for the choking actionand the segments are therefore non-uniformly distorted and vibrate uponfiring resulting in non-uniform shot patterns and irregular chokingaction. In other devices where more than one turn of the choke adjustingsleeve is required from open to full choke it is impossible to determinethe amount of choke unless the sleeve is moved to one extreme or theother and then adjusted to the desired choke. In other prior art devicesthe arrangement of parts is such that excessive friction exists betweenthe adjusting sleeve and the segments and it is manually diflicult toadjust the choke to the desired dete States Patent lgree. In otherdevices the arrangements of the elements thereof are such that they arereadily affected by weather conditions or the presence of dirt or burntpowder so that frequent cleanings and dismantlings of the device arerequired for accurate operation thereof.

All of these objections are overcome by the novel choke devices of thepresent invention and other advantages are inherent therein as will morefully appear hereinafter.

It is therefore an object of the present invention to provide noveladjustable muzzle chokes in which the segments are uniformly supportedthroughout their lengths to prevent undesirable or unusual distortionsthereof and to provide a uniform contraction for any choke position.

Another object is to provide such a choke in which the segments areconstantly flexed along their length in a uniform contraction and aresupported against vibration.

Another object is to provide such a choke having a micrometer adjustmentso that the same point on the micrometer scale is always reached for thesame number of turns of the choke adjusting sleeve.

Another object is to provide such a choke in which the supports for thesegments are line supports which change position with each change ofcurve of the segments and for each degree of choke utilized.

Another object is to provide such a choke in which the segments are ofconstant thickness at the positions of thickness thereof to insureuniform flexing of the segments.

Another object is to provide such chokes in which the ability of thesegments to flex along their full length compensates for any minorerrors occurring in the manufacture of the device to provide uniformadjustable choking.

Another object is to provide such chokes having a minimum of frictionbetween the moving parts to insure ease and rapidity of chokeadjustment.

Another object is to provide such chokes in which there is a positivelock of the choke adjusting sleeve at fully open and at fully chokedpositions.

Another and still further object of the present invention is to providesuch chokes which will provide longer service without cleaning becauseof the clearances provided between the moving elements thereof.

Other and still further objects of the present invention will appearfrom the following description of illustrative embodiments of the sameas will appear more fully hereinafter.

The novel adjustable muzzle chokes of the present invention are capableof various mechanical embodiments a number of which are shown in theaccompanying drawings and are described hereinafter to illustrate thesame. These illustrative embodiments of the present invention should inno way be construed as defining or limiting the same and referenceshould therefore 'be had to the appended claims to determine the scopeof this invention.

In the accompanying drawings in which like reference characters indicatelike parts, I

Fig. l is a view, partly in section, of the forwardly extending shell ofone embodiment of the present invention showing the shell threaded forengagement in a spacing device, not shown, and showing the position ofthe micrometer readings and the arrangement of the segments;

Fig. 2 is a view of the shell of Fig. I seen from the right therein;

Fig. 3 is a view partly in section of a suitable choke adjusting sleevefor use with the shell of Fig. 1 showing the conically tapered innersurface of the sleeve tapered in a curve of continuously increasingslope forwardly and inwardly toward the muzzle end thereof;

Fig. 4 is an end View of the sleeve of Fig. 1 as seen from the righttherein;

Fig. 5 is an axial sectional View of the shell of Fig. 1 and the sleeveof Fig. 3 in assembled position with the locking ring in position toprovide positive locking of the sleeve in open and in fully chokedposition;

Fig. 6 is a partial axial sectional view of another embodiment of thechoke device of the present invention in assembled condition showing thesegments supported by ball bearings;

Fig. 7 is a partial axial sectional view of another embodiment of thepresent invention in which the segments are supported by split rings;

Fig. 8 is an axial view partly in section of another embodiment of thepresent invention in which the segments are supported by a continuoushelix formed on the outer surfaces thereof and interrupted in the way ofthe slots between the segments;

Fig. 9 is an axial view partly in section of a modification of theembodiment of Fig. l and in which the choke device is designed formounting on the end of a shotgun barrel not employing a recoil absorbingor compensating device; and

Fig. 10 is an enlarged diagrammatic showing of the embodiment of Fig. 9to illustrate a method of obtaining the curve of the interior surface ofthe choke adjusting sleeve showing dimensions suitable for a chokedevice for use is formed into a plurality of forwardly extendingrelafively resilient segments 13 by slots 14 which extend parallel tothe axis of shell 10 from the forward end thereof to adjacent theshoulder 15. Any suitable number of slots 14 may be employed to provideany suitable number of segments 13 and as here shown there are six suchslots 14 and six such segments 13.

A plurality of uniformly spaced parallel lands or raised contactsurfaces 16;, separated by suitable grooves 17 are formedcircumferentially around the segments 13 at right angles to the axis ofshell 10 and are interrupted in way of slots 14. Grooves 17 mayterminate at their bottoms in the same cylindrical surface so that thethickness of segments 14 is uniform beneath all of the grooves 17 asshown at 18. The upper peripheral surfaces of lands 16 are rounded incross section as shown at 19 and the heights of lands 16 decreaseprogressively toward the muzzle of shell '10 so that parallel tangentsto the curved surfaces 19 will lie in a curve of the type generallyshown in Fig. 10.

A groove 20 is provided between shoulder and the adjacent land 16 toreceive the locking device, as will more fully appear hereinafter, andshell 10 is threaded at 21 to receive a choke adjusting sleeve to bedescribed with respect to Fig. 3. Shell 10 is provided between threads 9and threads 21 with a cylindrical surface 22 upon which suitablemicrometer readings 23 may be engraved to show suitable principal andintermediate choke positions.

Choke adjusting sleeve 24 is shown in Fig. 3. Sleeve 24 is internallythreaded at 25 for engagement with threads 21 of shell 10 and isprovided with a hollow cylindrical extension 26 which surrounds surface22 when the choke device is in assembled condition providing a shieldand a circumferential end .27 which cooperate with the micrometerreadings 23 to indicate the degree of choke of the device. Sleeve 24 iscircumferentially grooved at 28 to receive a split locking ring 29.Locking ring 29 is provided with an inwardly turned extension 30 whichpasses through hole 31 in sleeve 24 for movement in groove of shell 10.Sleeve 24 is provided with a tapered conical inner surface 32 curved asabove described.

The outer surface of sleeve 24 may be suitably knurled as to 33 tofacilitate rotation of the sleeve.

In assemblying the choke device of Figs. 1-5 sleeve 24 is inserted oversegments 13 and around the several lands 16 until threads engage threads21. Rotation of sleeve '24 in a clockwise direction as seen in Fig. 4then engages threads 25 and 21. Thereafter snap ring 29 is mounted ingroove 28 with extension extending through opening 31 and into groove 20of shell 10. Extension 30 abuts the adjacent land 16 when the chokedevice is in fully open position to prevent accidental removal or lossof sleeve 24 and abuts surface 15 of shell 11 when the choke device isin fully choked position thus providing a positive lock for the sleeve24 in both extreme positions of choke.

Since the outer surfaces of lands 16 are rounded in cross section, asdescribed above, it is apparent that the contact of each land withtapered conical surface 32 of sleeve 24 will be a circumferential linecontact providing reduced friction when sleeve 24 is rotated. It is alsoapparent that as sleeve 24 is rotated the circumferential line contactfor each land 16 will change in position around the curve surface of theland but that a uniform force will always be exerted on the land whichin turn is imparted to the segments 13. Since grooves 17 terminate inthe same cylindrical surface and are of uniform thickness beneath all ofthe grooves 17 as at 18 the segments 13 will be uniformly flexed anduniformly supported throughout their entire length thus preventingvibration of the segments 13 or undesired distortions thereof.

The embodiment of Fig. 6 differs from that of Figs. 1-5 in that thelands 16 are not employed and in place thereof ball hearings insnap-ring type races are used to ,4 support the segments 13. As shown inFig. 6, shell 10 is provided with an annular land 34 to act as a stopfor extension 30 of snap ring 29. Land 34 does not engage surface 32 ofsleeve 24. Shell 10 is provided with a plurality of spacedcircumferentially extending grooves 35 in which suitable snap-ring typeraces 36 are mounted to receive the ball bearings 37. Races 36 do notcompletely surround segments 13 and are spaced apart at their ends asshown at 38 to allow for contraction when sleeve 24 is rotated towardfully choked position.

Grooves 35 end in the same cylindrical surface so that the thickness ofsegments 13 may be uniform beneath the grooves 35 to insure uniformflexing of the segments. Races 36 and ball bearings 37 are chosen forsize and diameter, respectively, so that the points of contact of theseveral ball bearings 37 lie on surface 32 of sleeve 24.

In the embodiment of Fig. 6 the muzzle ends of segments 13 are roundedas at 38 to form a circumferential line contact with surface 32. Hereagain it is obvious that the segments 13 are provided with uniformsupport throughout their lengths; are prevented from vibration; areprevented from undesirable distortion; that friction between the movingelements is reduced to a minimum; and that clearances are provided whichallow long service of the device without cleaning.

The embodiment of Fig. 7 employs snap rings in place of the snap-ringtype ball bearing races of Fig. 6. In this embodiment shell 10 isprovided with a plurality of circumferential grooves 39 spaced apart andextending around the segments 13 and snap rings 40 are mounted ingrooves 39. Snap rings 40 are spaced apart at their ends, as shown at41, to allow for contraction of the rings when sleeve 24 is rotatedtoward choked position. Rings 40 are circular in cross section and aregraded in size fromlarger to smaller as the muzzle end of shell 10 isapproached so that each ring is in circumferential line contact withsurface 32 of sleeve 24. As surface '32 moves inwardly or outwardly tovary the choke it is obvious that the circumferential lines of contactwill shift but that a uniform support will always be provided forsegments 13 which prevents vibration and undesired distortion. Hereagain, the muzzle ends of segments 13 are rounded, as at 38, to providea circumferential line contact With surface 32 so that segments 13 areuniformly supported throughout their lengths by circumferential linecontacts acting to reduce friction at surface 32.

The embodiment of Fig. 8 differs from those described above in that acontinuous helix 42 of diminishing height toward the muzzle end of shell10 surrounds segments 13 and is interrupted in way of slots 14 to permitflexing of segments 13. The tops of the turns of helix 42 are rounded incross section as shown at 43 so that a helical line 'of contact is hadwith surface 32 of sleeve 24. The thickness of segments 13 between theturns of helix 42 is constant so that segments 13 will be uniformlyflexed by the action of sleeve 24. The turns of helix 42 gradedownwardly in height from the 'rearm'ost turn to the turn adjacent themuzzle end of shell 10 and are graded in height in accordance with cunve32 so as to continuously engage the sarne in a helical line of contact.The turns of helix 42 are spaced to provide sufiicient clearance so thatfrequent take down and cleaning of the device is not required.

In the embodiment of Fig. 8 the segments 13 are pro- 'VldCd with auniform support along their length and are flexed uniformly by theaction of surface 32 of sleeve 24 to prevent vibration of segments 13 orundesired dis tortions thereof. In this embodiment, as in those of Figs.6 and 7, the muzzle ends of segments 13 are rounded as at 38 to-pro videa circumferential line contact with surface 32 adjacent the muzzle endof shell 10. It is obvious that in this embodiment the line of contactwith surface 32 will change with the position of sleeve 24 Withoutchanging the uniform support of segments 13. Friction is reduced to a Apositivelock at fully opened and fully choked positions is provided byextension 30 of snap ring 29 and micrometer readings are obtainedbetween circumferential edge 27 and scale 23.

The embodiment of Fig. 9 is designed for direct mounting on the barrelof a shotgun. With this embodiment barrel 44 is provided with aninternal bore 45 and is externally threaded at 46 adjacent its muzzleend to receive internal threads 47 of shell 10. It is obvious that othermeans may be employed for securing shell 10 to barrel 44 and such meansmay include shrinking shell 10 upon shell 44, silver soldering shell 10on barrel 44 and the like.

Shell 10 is provided with internal bore 11 which is a continuation ofbore 45 and is also provided with an annular surface 22 upon which ring48 is suitably secured as at 49 by welding, silver soldering, shrinking,pinning or the like. Ring 48 covers a part of threads 21 which receiveinternal threads 25 of sleeve 24. Sleeve 24 is circumferentially groovedat 31 to receive split ring 29 and extension 30 thereof passes throughsleeve 24 and moves in grooves 20 to abut shoulder 15 in fully chokedposition and to abut the adjacent circumferential land 16 in fullyopened position. In this embodiment micrometer readings 23 are engravedin surface 50 of sleeve 24 and cooperate with the circumferential edge51 of ring 48 to show the choke setting of the device.

Fewer and shallower lands 16 are used in the embodiment of Fig. 9 andthe lands 16 are more widely separated. Here again the thickness ofsegments 13 is uniform beneath grooves 17 so that segments 13 will beuniformly flexed by the action of sleeve 24. The muzzle ends of segments13 are rounded as at 38 to provide a circumferential line contact withsurface 32 of sleeve 24 and the height of lands 16, which are rounded incross section to provide circumferential line contacts with surface 32,are selected in accordance with the shape of surface 32 so that uniformsupport is provided at all times throughout the length of segments 13.Lands 16 are, of course, interrupted in way of slots 14, as is seen at52, to allow flexing of segments 13.

The embodiment of Fig. 9 of the present invention provides the desireduniform flexing of segments 13 with uniform suppport of segments 13throughout their length to prevent vibration and undesired distortionthereof while at the same time reducing friction between the movingparts with clearance therebetween suflicient to permit long use of thedevice without disassembly for cleaning. The micrometer reading isaccurate and exact and the moving parts are provided with maximumprotection against the entry of dirt.

Fig. 10, which is enlarged, and not to scale, shows suitable dimensionsfor the embodiment of Fig. 9 for an adjustable muzzle choke for a twelvegauge shotgun.

The dimensions are in inches and from such dimensions the shape of curvesurface 32 can be readily determined. The shape of curve 32 isdetermined in part by the number of turns of sleeve 24 which are desiredto flex segments 13 from fully opened position to fully choked position.The internal diameter at the muzzle of segments 13 for a twelve gaugeshotgun at fully open position may be .750 inch based upon thelongitudinal length from the muzzle of the shotgun. All of these figuresare variable and are based on the dimensions of the Cutts Compensatorwhich are well known. This diameter is .725 inch for modified choke and.705 inch for full choke. Thus the difference of the diameter betweenfully open and fully choked positions is .045 inch and if three turnsare employed to effect this choke then the diameter at the muzzle mustbe reduced .015 inch for each turn of sleeve 24. If threads 21 and 25'are twenty turns to the inch then the distance which surface 32 moveslongitudinally for one turn of sleeve 24 is .05 inch. The pitch of curve32 extending away from the line of contact of surface 38 at fully openedposition is therefore .015 inch on .05 inch. Similar calculations foreach of the cir- 6 cumferential line contacts for each land 16 can becal culated in similar manner and the shape of curve surface 32 therebydetermined.

It will now be apparent to those skilled in the art that by the presentinvention I have provided an adjustable muzzle choke which in every waysatisfies the several objectives discussed above.

Changes in or modifications to the illustrative embodiments of myinvention may now be suggested without departing from the presentinventive concept. For ex ample, the internal curve surface describedabove for sleeve 24 may be transposed to the outer surfaces of segments13 and the various lands, ball bearing races, split rings, and helix, asdescribed above, transferred to the inner surface of sleeve 24. Further,if non-uniform flexing is desired for segments 13 at any given point thethickness may be reduced at that point, as by annular grooving, toprovide the desired flexing. It is to be emphasized, however, that Iprefer a uniform thickness of segments 13, as described above, to give auniform flex throughout their length. In view of the above, referenceshould therefore be had to the appended claims to determine the scope ofthis invention.

What is claimed is:

1. In an adjustable muzzle choke for shotguns having a plurality ofresilient axially extending circumferentially disposed segments and asleeve longitudinally movable over said segments, means for flexing anduniformly supporting said segments along their length in cluding aninternal surface in said sleeve tapered in a curve of continuouslyincreasing slope forwardly and inwardly toward the muzzle end thereofand a plurality of circumferentially disposed spaced substantiallyparallel raised contact surfaces on said segments of progressivelydecreasing heights toward the muzzle end of said segments, said segmentshaving uniform thickness between said raised contact surfaces, saidraised contact surfaces having their surfaces of contact rounded incross section and engaging said internal surface in circumferentiallines of contact which change position with each change of curve of thesegments and for each degree of choke utilized.

2. A muzzle choke as described in claim 1 in which the muzzle ends ofsaid segments have outer surfaces rounded in cross section and engagingsaid internal surface in a circumferential line of contact which changesposition with each change of curve of the segments and for each degreeof choke utilized.

3. In an adjustable muzzle choke for shotguns having a plurality ofresilient axially extending circumferentially disposed segments and asleeve longitudinally movable over said segments, means for flexing anduniformly supporting said segments along their length including aninternal surface in said sleeve tapered in a curve of continuouslyincreasing slope forwardly and inwardly toward the muzzle end thereofand a plurality of circumferentially disposed spaced substantiallyparallel raised contact surfaces on said segments interrupted betweensaid segments and of progressively decreasing heights toward the muzzleend of said segments, said segments having uniform thickness betweensaid raised contact surfaces, said raised contact surfaces having theirsurfaces of contact rounded in cross section and engaging said internalsurfaces in circumferential lines of contact which change position witheach change of curve of the segments and for each degree of chokeutilized.

4. In an adjustable muzzle choke for shotguns hav ing a plurality ofresilient axially extending circumferentially disposed segments and asleeve longitudinally movable over said segments, means for flexing anduniformly supporting said segments along their length including aninternal surface in said sleeve tapering in a curve of continuouslyincreasing slope forwardly and inwardly toward the muzzle end thereofand a plurality of circumferentially disposed spaced parallel lands onsaid segments interrupted between said segments and of progressivelydecreasing heights toward the .muzzle end of said segments, saidsegments having uniform thickness between said lands, said lands havingouter surfaces rounded in cross section and engaging said internalsurface in circumferential lines of contact which change position witheach change of curve of the segments and for each degree of chokeutilized.

5. A muzzle choke as described in claim 4 in which the muzzle ends ofsaid segments have outer surfaces rounded in cross section and engagingsaid internal surface in a circumferential line of contact which changesposition with 'each change of curve 'of the segment and for each degreeof choke utilized. References Cited inthe "file of this patent UNITEDSTATES PATENTS 1,348,750 Schuster Aug. .3, 192-0 2,335,138 White Nov.23, 1 943 2,398,298 Finlay et al. Apr. 9, 1946 2,442,899 McAllister June'8, 1948 2,453,747 Egleson Nov. 16, 1948 2,476,438 Wright July 19, 19492,676,429

Gotterson Apr. 27, 1954

